Congenital And Cystic Renal Disease Flashcards
1
Q
Gross Anatomy of the Kidney:
- Cortex
- Medulla
A
- Cortex
- usually ~ 1 cm thick, contains glomeruli, proximal tubules and distal tubules
- Medulla
- divided into 8-18 medullary pyramids and contains loops of Henle and collecting ducts
2
Q
1-1.5 million nephrons composed of:
A
-
Glomerulus –
- supplied by afferent arteriole ⇒ glomerular capillaries ⇒ efferent arteriole
-
Proximal tubule –
- first segment of nephron after Bowman’s capsule
- epithelium with brush border
-
Loop of Henle –
- begins at transition from thick-walled to thin-walled tubule
-
Distal tubule –
- thick ascending limb merges with distal tubule
-
Collecting duct –
- receives ~6 distal tubules and enters medulla
- join each other to form ducts of Bellini which drain into calyx
3
Q
Describe the Glomerular Endothelial Cells:
A
- Fenestrated (70-100 nm)
- Negatively charged surface
- Form initial filtration barrier
- Synthesize and maintain GBM
4
Q
What is the Glomerular Basement Membrane (GBM)?
A
- Composed Type IV collagen
- Size and charge are main determinants of filtration:
- Heparan sulfate provides negative charge
- Water and cationic proteins of LMW (are permeable
- Albumin permeability is limited by its negative charge
5
Q
What is the role of the Visceral Epithelial Cells (Podocytes)?
A
- Also synthesize and maintain GBM
- Cytoplasmic foot processes form filtration slit (slit pore)
- Podocytes are negatively charged
6
Q
What is the role of the Mesangial Cells?
A
- Cell cytoplasm contains myosin filaments
- Cells are surrounded by GBM like matrix
- Provides structural support
- Modulate glomerular filtration
7
Q
What are the different types of congenital renal abnormalities?
A
- Aplasia, Hypoplasia, dysplasia
- Ectopic kidneys
- Fusion abnormalities
- Duplication of ureters
8
Q
- What is the most common congenital kidney disorder?
- What are characteristics of this disorder?
A
Horseshoe Kidney
- 90% are fused at the lower pole
- Increased incidence with Turner’s syndrome
- Increased risk of infection and kidney stones
9
Q
Renal Dysplasia:
- **Incidence: **
- Detection:
A
-
Incidence:
- Unilateral – 1 in 4,300 live births
- Combined incidence – 1 in 3,600
-
Detection:
- Prenatal ultrasound
- Palpable mass
- Asymptomatic (undetected into adulthood)
10
Q
What is the genetic defect in Autosomal Recessive PKD?
A
PKHD1 gene located on chromosome 6p21
- Can be diagnosed in utero by ultrasound:
- large hyperechoic kidneys
- oligohydramnios
- decreased urine in fetal bladder
11
Q
How does ARPKD present?
A
- Enlarged kidneys at birth
- Serious cases incompatible with life
- Perinatal mortality 30-50%
- Associated with maternal oligohydramnios
- Potter’s facies
- Pulmonary hypoplasia
12
Q
What are the main extrarenal manifestations of ARPKD?
A
- Hepatic fibrosis
- Cholangitis
- Portal hypertension
- esophageal varices
- GI bleeding
13
Q
**ARPKD: **
Morphology
A
-
Smooth kidney with numerous small cysts
- Cortical and medullary cysts
- Cut section – cylindrical cysts extending radially through cortex
- Microscopically – cysts lined by cuboidal epithelium; may see epithelial hyperplasia
- Glomeruli normal
14
Q
- How is family hx relevant in Autosomal Dominant PKD?
- What is the genetic defect in Autosomal Dominant PKD?
A
- Affects 1:400 - 1:1000 Americans
-
Family history absent in 25-40%
- new mutations
- late-onset renal failure
-
90% have mutation of PKD1 gene on chr. 16
- Others have mutation of PKD2 gene on chr. 4
- Patients with PKD2 mutations progress to renal failure at a later age than PKD1
15
Q
ADPKD
Cyst Formation
A
- Abnormal differentiation of epithelial cells
- High proliferation rate
- Secretion of fluid into cysts with loss of connection to functioning nephrons
- Abnormal extracellular matrix
21
Q
- Describe the cysts associated with Acquired Cystic Disease:
- What can Acquired Cystic Disease lead to?
A
-
Clear, fluid-filled cysts
- Uni- or multilocular cysts
- Cortex (usually), may involve corticomedullary junction and medulla
- Increased incidence of papillary renal cell carcinoma
